The present invention relates to an electromagnetic switch matrix device for use in automatic exchanges, hybrid electronic computers and the like.
Generally, in known of electromagnetic switch matrix devices, by selectively applying a current pulse to a row control line and a column control line, magnetic cores which are easily reversible in magnetization and capable of retaining residual magnetization, are controlled so that a magnetically responsive switching element located at a cross point between a row signal line corresponding to said row control line and a column signal line corresponding to said column control line may be closed to connect said row signal line to said column signal line.
In this case, at each cross-point where the row signal line and the column signal line intersect at right angles to each other, there are provided a plurality of excitation windings for electromagnetically controlling said switching element, which windings are connected to the corresponding row control line or to the corresponding column control line. In order to select and close a particular switching element, a current pulse is applied to the corresponding row control line and the corresponding column control line to energize the excitation windings, and thereby the switching element is closed.
However, in the above-described construction, in which the switching element is selected by logical coincidence of the directions of the applied magnetic fields, the total magneto-motive force applied upon selection of the switching element would become fairly large in comparison with the magneto-motive force required for closing the switching element, because two sets of the excitation windings arranged along the row and the column are simultaneously energized. Accordingly, the impedance of the windings would be very high, and the driving electric power would be also large.
In addition, the switching elements are adapted to be released if the excitation winding or windings belonging to only one of the associated row and column control lines are energized. Therefore, when the switching element at a particular cross-point is actuated to close its contact points, all the switching elements located at the other cross-points on the same row and on the same column are automatically released, and so it is difficult to realize multiple connection of the switching elements located on the same row or on the same column.
Furthermore, in such prior art switch matrix devices, it is a common practice to provide, as the excitation windings for each switching element, two pairs of windings having different numbers of turns and different directions of turns from each other, each pair being connected to one of the row and column control lines. Accordingly, owing to the excitation windings having a large number of turns, the magnetic interference between adjacent rows or between adjacent columns becomes large, so that the spacing of the cross-points is inevitably large.